Robot hand coupling assembly

ABSTRACT

A robot hand changer has a first joint member mounted on a robot arm, a second joint member mounted on a robot hand, and an engaging member mounted on the first joint member and angularly movable with respect to the second joint member for coupling the first and second joint members against each other. The robot hand changer also has an optical signal transmission device including sets of optical fibers disposed in confronting relation out of contact with each other for transmitting control signals across mating surfaces when the robot arm and the robot hand are coupled to each other, and photoelectric transducer circuits for converting electric signals to optical signals and vice versa. The robot hand arm further includes a detecting device for detecting dirt on the mating surface.

BACKGROUND OF THE INVENTION

The present invention relates to a robot hand changer, and moreparticularly to a robot hand changer for automatically attaching a handfor gripping a workpiece or effecting other operations, detachably to arobot, and for reliably and accurately mounting a hand to a robot evenif the hand is relatively heavy, the device being capable of easilytransmitting control signals and the like between the robot and the handand being highly reliable in sufficiently withstanding frequentconnection and disconnection between the robot and the hand.

In recent years, factories have seen widespread use of robots forautomatically machining, conveying, and assembling workpieces tomass-produce products efficiently. The robots are generally designed toeffect single operation. Since however many factories produce a widevariety of different products, there has been a demand for amultifunction robot which can perform different kinds of operation.

To meet such a demand, there has been proposed a robot hand changer forselectively attaching hands for machining, conveying, assemblingworkpieces detachably to a robot, so that the single robot can performmany types of operation with the use of desired hands.

A robot hand for gripping a passenger seat to install the same in anautomobile body is relatively large and heavy. Since such a robot handimposes a considerable load on a joint to a robot body, it ispractically impossible to rely on a robot hand changer for use with therobot hand. Therefore, a robot hand changer has heretofore been employedto change relatively light hands, and hence a robot finds limitedfunctions.

Lead wires, optical fibers, and pipes for supplying mediums to actuate ahand or a tool are exposed, and hence are susceptible to damage underexternal forces during operation of the robot.

The robot body and the hand are required to be not only mechanicallycoupled to each other, but also have an easily detachable constructionwhich can supply electric power, transmit control signals, and deliver ahydraulic or pneumatic fluid for actuating the hand, between the robotbody and the hand.

The control signals to be transmitted between the robot body and thehand is fed through many electric cables which are coupled by aconnector. Where the hand is replaced with others at frequent intervals,the durability of the connector may be reduced by frequent connectionand disconnection thereof. Recently, efforts have been made to eliminatethe mechanical connection in signal transmission by employing a magneticconnector in place of the mechanical connector or an optical connectorthrough which optical signals converted from electric signals aretransmitted. In case magnetic sensors are used in the connector, theyare subject to disturbance arising from an external magnetic field andtake up a large space since as many magnetic sensors are disposed as thenumber of electric cables used. Where optical control signals aretransmitted through a single optical fiber, parallel control signalscorresponding to the electric cables are converted to serial signals fortransmission and the serial signals which are received are convertedback to parallel signals. Converters required for suchparallel-to-serial and serial-to-parallel signal conversion make theentire system complex and costly.

SUMMARY OF THE INVENTION

It is a general object of the present invention to provide a robot handchanger which can easily and reliably mount a hand that is relativelylarge and heavy on an arm of a robot.

A major object of the present invention is to provide a robot handchanger by which pipes for supplying a medium to actuate a robot hand ora tool, and signal wires for electric control can quickly and reliablybe connected between the robot hand and a robot arm without beingexposed, so that no malfunction or failure will be experienced and highdurability will be ensured for the pipes and the signal wires.

Another object of the present invention is to provide a robot handchanger in which a first joint member is mounted on a robot arm, asecond joint member is mounted on a robot hand, and engaging means ismounted on one of the first and second joint members and angularlymovable with respect to the other joint member for pressing the firstand second joint members against each other. Lead wires, optical fibers,and pipes for supplying hand actuating mediums, the lead wires areprovided. The optical fibers, and the pipes are not exposed. The robothand changer is capable of mounting the robot hand, even if it isrelatively heavy, firmly and accurately on the robot arm. The robot handchanger of the present invention is highly versatile.

Still another object of the present invention is to provide a robot handchanger having an optical signal transmission device including sets ofoptical signal transmitting means such as optical fibers disposed inconfronting relation out of contact with each other for transmittingcontrol signals across mating surfaces when the robot arm and the robothand are coupled to each other. The robot hand changer also includesphotoelectric transducer circuits, so that the control signals can betransmitted without using mechanical coupling means, and the robot handcan easily be detached and attached even if hand replacement is highlyfrequent, the optical signal transmission device being highly durableand reliable.

Yet still another object of the present is to provide a robot handchanger having optical signal transmitting means capable of detectingdirt on mating surface of a robot hand and a robot arm.

A further object of the present invention is to provide a robot handchanger comprising a first joint member adapted to be mounted on a robotarm, a second joint member adapted to be mounted on a robot hand, meansfor supplying a hand actuating medium through said first and secondjoint members to the robot hand, actuator means, and engaging meansmounted on one of said first and second joint members and angularlymovable by said actuator means for detachably coupling said first andsecond joint members.

A still further object of the present invention is to provide a robothand changer comprising a first joint member adapted to be mounted on arobot arm, a second joint member adapted to be mounted on a robot hand,said first and second joint members being coupled to detachably connectsaid robot hand to said robot arm, at least one set of optical signaltransmitting means mounted in said first and second joint members inconfronting relation out of contact with each other for transmittingcontrol signals across mating surfaces of said robot hand and said robotarm, and photoelectric transducer circuits adapted to be disposed insaid robot hand and said robot arm, respectively, for converting anoptical signal received via said optical signal transmitting means toelectric signals and/or converting an optical signal transmitted viasaid optical signal transmitting means from electric signals.

The above and other objects, features and advantages of the presentinvention will become more apparent from the following description whentaken in conjunction with the accompanying drawings in which a preferredembodiment of the present invention is shown by way of illustrativeexample.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an exploded perspective view, partly cut away, of a robot handchanger according to the present invention, showing the robot handchanger as being separated;

FIG. 2 is a fragmentary cross-sectional view of the robot hand changershown as being coupled;

FIG. 3 is a cross-sectional view taken along line III--III of FIG. 2;

FIG. 4 is an elevational view illustrating coupling operation of therobot hand changer;

FIG. 5 is a perspective view of a sheet gripping hand mounted on a robotby the robot hand changer;

FIG. 6 is a view, partly in cross section, of an optical signaltransmission device;

FIG. 7 is a diagram showing a means for detecting dirt on matingsurfaces;

FIG. 8 is a diagram showing characteristics of a photoelectrictransducer device;

FIG. 9 is a diagram showing another means for detecting dirt on matingsurfaces; and

FIG. 10 is a diagram of the waveforms of signals in the arrangementshown in FIG. 9.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

As shown in FIGS. 1 and 2, a robot hand changer according to the presentinvention includes a main changer assembly 10 comprising a first jointmember 12 to be mounted on a robot body, an engaging member 14 rotatablyfitted over the first joint member 12, and a second joint member 16mounted on a hand and coupled to the first joint member 12 through theengaging member 14.

The first joint member 12 is of a substantially cylindrical shapeincluding a flange 18 on one axial end thereof, the flange 18 having aplurality of bolt insertion holes 20 extending in the axial directionthereof. The first joint member 12 has a pair of parallel casings 22a,22b extending radially outwardly in a direction normal to the axialdirection of the first joint member 12. A cylindrical member 24 extendsaxially from an end of the casings 22a, 22b and includes alarger-diameter portion 26 on its end (see FIG. 2). Cylinder mechanisms28a, 28b are mounted on the casings 22a, 22b, respectively.

As illustrated in FIG. 3, the casing 22a has chambers 30a, 30b definedin its opposite end portions, respectively, with pistons 32a, 32b beingaxially slidably fitted respectively in the chambers 30a, 30b. Thepistons 32a, 32b are fixedly mounted on the opposite ends of a rod 34having an axially extending rack 36 on an outer peripheral surfacethereof. The chambers 30a, 30b are closed by respective covers 38a, 38bfixed to the opposite ends of the casing 22a. To the covers 38a, 38b,there are coupled ends of fluid pipes 40a, 40b, respectively, the otherends of which are connected to a fluid pressure source (not shown).

Likewise, a rod 34a having a rack 36a is displaceably fitted in thecasing 22b (see FIG. 2). The casing 22b has its opposite ends closed byrespective covers 38c, 38d fixed thereto to which respective fluid pipes40c, 40d are connected. The racks 36, 36a of the rods 34, 34a are heldin mesh with the engaging member 14.

The engaging member 14 is of a cylindrical shape having a pinion 42 onits outer periphery at one end thereof, the pinion 42 meshing with theracks 36, 36a (FIG. 3). The engaging member 14 has a stepped hole 44defined centrally therein and includes a plurality of radially inwardlyprojecting teeth 46a through 46h in a larger-diameter portion of thestepped hole 44. The teeth 46a through 46h are circumferentially equallyspaced and have respective inner engaging surfaces 48a through 48h (seeFIG. 4) tapered or slanted axially toward adjacent teeth in thedirection of the arrow A in which the engaging member 14 is tightened.The engaging member 14 is rotatably fitted over the first joint member12 by means of bearings 47a, 47b on the cylindrical portion 24 and thelarger-diameter portion 26 of the first joint member 12, with the pinion42 meshing with the racks 36, 36a.

A stepped hole 50 is defined centrally in the larger-diameter portion 26of the first joint member 12, with a disc 52 being fixedly fitted in thestepped hole 50. The disc 52 comprises, as an integral structure, amanifold 56 having a plurality of fluid ports 54 and a holder plate 60supporting a plurality of optical fibers 47 and connector terminals 58.Positioning pins 62a, 62b (FIG. 1) are threaded in the front face of thelarger-diameter portion 26 of the first joint member 12.

The second cylindrical joint member 16 has a plurality of equallycircumferentially spaced teeth 64a through 64h projecting radiallyoutwardly from an outer circumferential surface of the second jointmember 46 at one end thereof, the teeth 64a through 64h being positionedfor engagement with the teeth 46a through 46h, respectively, of theengaging member 14. The teeth 46a through 46h have engaging surfaces 66athrough 66h, respectively, tapered or slanted complementarily to theslanted surfaces 48a through 48h of the teeth 46a through 46h. The outerperipheral surfaces of the teeth 64a through 64h jointly define animaginary circle the diameter of which is smaller than the diameter ofthe larger-diameter portion of the stepped hole 44 in the engagingmember 14. The teeth 64c, 64g have holes 67a, 67b defined therein in theaxial direction of the second joint member 16. The positioning pins 62a,62b of the first joint member 12 are fitted respectively in the holes67a, 67b for positioning the first and second joint members 12, 16 withrespect to each other.

A disc 70 is fixedly mounted in a stepped hole 68 defined centrally inthe second joint member 16. The disc 70 comprises, as an integralstructure, a manifold 74 having a plurality of fluid ports 72 and aholder plate 78 supporting a plurality of optical fibers 75 andconnector terminals 76. When the first and second joint members 12, 16are joined to each other, the discs 70, 52 are held against each otherto provide communication between the fluid ports 72, 54 and connectionbetween the connector terminals 76, 58.

The first joint member 12 is mounted on an robot arm 80 (FIG. 2) bybolts or the like passing through the holes 20 in the flange 18. Thesecond joint member 16 is mounted on a hand 82 (FIG. 5) for gripping anautomobile passenger seat, for example. Therefore, the manifold 74 andthe holder plate 78 which are fixed to the second joint member 16 arecoupled to fluid pipes 84, optical fibers 75, and lead wires 86 that arenecessary for actuating the seat gripping hand 82. The manifold 56 andthe support plate 60 fixed to the first joint 12 are connected to fluidpipes 88, optical fibers 57, and lead wires 90, the number of which isat least equal to the number of the fluid pipes 84, optical fibers 75,and lead wires 86. The fluid pipes 88, the optical fibers 57, and thelead wires 90 are housed in the first joint member 12 and coupled to therobot body (not shown) through the robot arm 80.

Mechanical operation of the robot hand changer thus constructed formounting the seat gripping hand 82 on the robot arm 80, for example,will be described hereinbelow.

As shown in FIG. 1, the first and second joint members 12, 16 arepositioned in axially confronting relation and displaced toward eachother. The teeth 46a through 46h of the engaging member 14 are initiallyin an angular position different from the angular position of the teeth64a through 64h of the second joint member 16. Therefore, the secondjoint member 16 is loosely fitted into the stepped hole 44. Thepositioning pins 62a, 62b threaded in the first joint member 12 arefitted respectively into the holes 67a, 67b of the second joint member16 to position the first and second joint members 12, 16 relatively toeach other. The discs 52, 70 are brought into abutment against eachother to connect the manifolds 56, 74 and the holder plates 60, 78.Therefore, the pipes 84, 88 are coupled to each other, the opticalfibers 57, 75 are optically connected to each other, and the lead wires86, 90 are electrically connected to each other.

Then, as shown in FIG. 3, the cylinder mechanisms 28a, 28b are actuated.More specifically, the cylinder mechanism 28a on the casing 22a operatesas follows: A fluid is supplied from the pipe 40a into the chamber 30ain the casing 22a to push the piston 32a in the direction of the arrow Bfor thereby displacing the rod 34 coupled to the piston 32a in thedirection of the arrow B. Consequently, the pinion 42 meshing with therack 36 on the rod 34 is rotated about its own axis in the direction ofthe arrow A, and so is the engaging member 14 having the pinion 42. Theteeth 46a through 46h are angularly displaced with the engaging member14 in the direction of the arrow A to bring the engaging surfaces 48athrough 48h of the teeth 46a through 46h into contact with the engagingsurfaces 66a through 66h of the teeth 64a through 64h. The engagingsurfaces 48a through 48h are slanted toward the second joint member 16in the direction in which the engaging member 14 is tightened (in thedirection of the arrow A), and the engaging surfaces 66a through 66h areslanted complementarily to the engaging surfaces 48a through 48h (seeFIG. 4). Continued rotation of the engaging member 14 in the directionof the arrow A thus press the engaging surfaces 48a through 48h and theengaging surfaces 66a through 66h firmly against each other through awedging action. At this time, the cylinder mechanism 28b on the casing22b is similarly operated by supplying a fluid from the pipe 40d intothe casing 22a to displace the rod 34a in the direction of the arrow C.The pinion 42 meshing with the rack 46a of the rod 34a is thus rotatedin the direction of the arrow A by the displacement of the rod 34a. As aresult, pinion 42 is rotated by the combined movement of the rods 34,34a to couple the first and second joint members 12, 16 firmly to eachother.

After the seat gripping hand 82 is mounted on the robot arm 80, oil orair under pressure is supplied from the pipes 88 to the pipes 84 todrive cylinders or the like of the seat gripping hand 82. Opticalsignals are supplied from the optical fibers 57 to the optical fibers75, and electric signals are fed from the lead wires 90 to the leadwires 86 to energize motors or the like of the seat gripping hand 82,for thereby enabling the seat gripping hand 82 to grip the seat 92, asshown in FIG. 5.

The robot hand changer of the present invention can mount the seatgripping hand 82 which is relatively large and heavy on the robot arm80. More specifically, the first and second joint members 12, 16 arecoupled firmly to each other by the teeth 64a through 64h of the secondjoint member 16 and the teeth 46a through 46h of the engaging member 14which is rotatably fitted over the first joint member 12. Since theteeth 64a through 64h and 46a through 46h have the slanted engagingsurfaces 66a through 66h and 48a through 48h, respectively, the load ofthe seat gripping hand 82 is not imposed locally on the main changerassembly 10. The first and second joint members 12, 16 are firmlyanchored to each other because the engaging surfaces 48a through 48h and66a through 66h are held in engagement with each other through a wedgingaction. Therefore, the large and heavy seat gripping hand 82, which hasheretofore been unable to be used with a robot hand changer, canreliably and accurately be mounted on the robot arm 80. The first andsecond joint members 12, 16 can be securely coupled to each otherbecause the engaging member 14 is turned by the two cylinder mechanisms28a, 28b through their combined movement.

In the robot hand changer according to the embodiment of the presentinvention, the pipes 84, the optical fibers 75, and the lead wires 86for actuating the seat gripping hand 82 are not exposed out. Morespecifically, when the first and second joint members 12, 16 are joinedto each other, the discs 52, 70 are held against each other to couplethe manifolds 56, 74, connect the optical fibers 57, 75 optically, andconnect the connector terminals 58, 76 electrically. With as many pipes88, optical fibers 57, and lead wires 90 being supported by the disc 52in the first joint member 12 as the number of the pipes 84, opticalfibers 75, and lead wires 86, an operating medium, control signals, andelectric power can easily be supplied to the seat gripping hand 82. As aconsequence, the pipes, the optical fibers, and the lead wires are freefrom damage or breakage which would otherwise be caused if they wereexposed as is the case with the conventional arrangements.

The seat gripping hand 82 can be detached from the robot arm 80 asfollows:

While the second joint member 16 is being placed on a hand rest or thelike, a fluid is supplied under pressure from the pipes 40b, 40c intothe casings 22a, 22b. The fluid supplied under pressure into the chamber30b in the casing 22a pushes the piston 32b in the direction of thearrow C, so that the rod 34 coupled to the piston 32b is displaced inthe direction of the arrow C to enable the rack 36 to rotate the pinion42 in the direction of the arrow D. The fluid supplied under pressurefrom the pipe 40d displaces the rod 34a in the direction of the arrow B,thus rotating the pinion 42 meshing with the rack 36a in the directionof the arrow D. Therefore, the engaging member 14 having the pinion 42is rotated in the direction of the arrow D to cause the teeth 46athrough 46h to move out of contact with the teeth 64a through 64h forthereby releasing the engaging surfaces 48a through 48h and 66a through66h from wedging engagement. When the teeth 46a through 46h and 64athrough 64h are brought into different angular positions, the cylindermechanisms 28a, 28b are inactivated, and the first and second jointmembers 12, 16 are relatively displaced away from each other until thesecond joint member 16 is moved out of the stepped hole 44. As a result,the robot arm 80 and the seat gripping hand 82 are separated from eachother. Another desired hand may then be mounted on the robot arm 80 inthe same manner as described above for effecting a next operation.

An optical signal transmission device used with the robot hand changerfor transmitting control signals through optical fibers will bedescribed below.

As shown in FIG. 6, the holder plate 60 supports the connector terminals58 for a power supply and the optical fibers 57, and is disposed int hefirst joint member 12 connected to the robot body. Similarly, the holderplate 78 supports the connector terminals 76 for a power supply and theoptical fibers 75, and is disposed in the second joint member 12connected to the robot hand. A photoelectric converter circuit 102disposed int he robot hand serves to convert control signals LSl throughLSn (electric signals) indicative of operating conditions of variousparts of the robot hand to optical signals through light-emittingelements or the like, and to apply the optical signals to the opticalfibers 75. A photoelectric transducer circuit 104 disposed in the robotbody serves to convert the optical signals received from the opticalfibers 57 to electric signals through photocouplers or the like. Anindicator panel 106 indicates the status of the control signals LSlthrough LSn with light-emitting elements 108. Electric power is suppliedfrom the power supply via power supply lines P1, P2, lead wires 90, andthe connector terminals 58, 76 to lead wires 86. Coil springs 110 actingon the connector terminals 58 are effective to press the connectorterminals 58 against the connector terminals 76 when the robot body andthe robot hand are joined to each other. The optical fibers 57 and theoptical fibers 75 are held by the holder plates 60, 78, respectively, sothat the optical fibers 57, 75 will be positioned in face-to-facerelation when the robot body and the robot hand are coupled to eachother.

The optical signal transmission device operates and offers advantages asfollows:

As described above with reference to FIGS. 1 through 4, when the robotarm 80 and the seat gripping hand 82 are coupled to each other by thefirst and second joint members 12, 16, the electric power is suppliedfrom the robot body to the robot hand through the connector terminals58, 76. The electric signals LSl through LSn representative of theoperating conditions of the components of the robot hand are convertedto optical signals by the photoelectric transducer circuit 102, and theoptical signals are led by the optical fibers 75 to mating surfaces 112of the holder plates 60, 78. The mating surfaces 112 are slightly spacedfrom each other when the first and second joint members 12, 16 arecoupled. The optical signals from the optical fibers 75 are transmittedto the confronting optical fibers 57, and their status is indicated onthe display panel 106 by the light-emitting elements 108 mountedthereon.

The optical signals transmitted to the optical fibers 57 are convertedback to electric signals by the photoelectric transducer circuit 104,and the electric signals are then transmitted to a sequence control unitin the robot body for controlling movement of the robot hand.

The electric signals are converted to corresponding optical signals intwo states represented by energization and de-energization of thelight-emitting elements in the photoelectric transducer circuit 102.Therefore, even if the optical fibers 75, 57 are positioned somewhat outof axial alignment with each other, the signals can be transmittedtherebetween unless a large transmission loss were caused by substantialaxial misalignment between the optical fibers 75, 57. To avoid suchtransmission loss, it is preferable that the joint members 12, 16 andthe holder plates 60, 78 be of high mechanical accuracy so that theoptical fibers 75, 57 will face each other in each pair at the matingsurfaces 112 with high accuracy.

When the first and second joint members 12, 16 are interconnected, theoptical fibers 75, 57 are out of contact with each other since themating surfaces 112 are slightly spaced from each other. Even if robothands are changed highly frequently, therefore, the optical fibers 75,57 will not be damaged at their confronting ends as they do not engageeach other, and hence the optical fibers 75, 57 have increaseddurability and reliability.

FIG. 7 shows a detecting means for detecting dirt on the mating surfacesof the robot arm and the robot hand, in the signal transmission meansillustrated in FIG. 6. Since robots that can be used in combination withthe present invention are employed in factories, the joint between therobot arm and the robot hand tends to be smeared with oil and dustdeposits. If the end faces of the optical fibers in the signaltransmission means of the invention for transmitting optical controlsignals were smeared with oil and/or dirt, the transmission loss wouldbe increased, a condition which is not preferable.

The detecting means shown in FIG. 7 is designed to solve the aboveproblem. One of the signals LS indicative of the operating conditions ofthe parts of the robot hand, e.g., a signal LS0, is used. This signal isapplied to energize a light-emitting element 114 in the photoelectrictransducer circuit 102 at all times while the robot arm and the robothand are being coupled to each other, for thereby transmitting anoptical signal into the optical fiber 75. The optical signal passes fromthe optical fiber 75 across the mating surfaces 112 into the opticalfiber 57, from which the optical signal is fed to the photoelectrictransducer circuit 104 in which the optical signal is converted to anelectric signal by a photocoupler 116. The level L of light representedby the optical signal transmitted through the optical fibers 75, 57 isrelated to the output voltage level V of the photoelectric transducerelement such as the photocoupler as shown in FIG. 8. That is, as thelight level L increases, the output voltage goes higher at aproporational rate. The output from the photocoupler 116 is applied toone input terminal of a differential amplifier 118. By selecting areference voltage V1 applied to a reference voltage terminal 120 of thedifferential amplifier 118, the sensitivity of the photoelectricconversion process can be established.

For example, as shown in FIG. 8, a sensitivity V2 is set for a normalsignal light level, whereas a sensitivity V1 is set for a signal lightlevel which is lower than the normal signal light level. With thisarrangement, a reduction in the light level due to a dirt deposit on themating surfaces can reliably be detected.

FIG. 9 shows another means for detecting dirt on the mating surfaces. Inthis embodiment, a signal LS0 representing that the robot arm and therobot hand are coupled is applied to a timer circuit 121. In response toan output signal from the timer circuit 121, all of the signals LSlthrough LSn indicative of the operating conditions of the parts of therobot hand are rendered high or ON for a preset period of time after therobot arm and the robot hand have been coupled, so that alllight-emitting elements in the photoelectric transducer circuit 102 areenergized to transmit optical signals from the optical fibers 75 acrossthe mating surfaces 112 into the optical fibers 57. The optical signalsare then converted to electric signals by photoelectric transducerelements such as photocouplers in the photoelectric transducer circuit104.

The sensitivity of each of the photoelectric transducer elements in thephotoelectric transducer circuit 104 is set to a sensitivity level V1 asdescribed with reference to FIGS. 7 and 8 for detecting dirt on themating surfaces in the same manner as in the embodiment of FIGS. 7 and8.

FIG. 10 shows signal waveforms indicative of operation of thearrangement of FIG. 9. LS0 represents a condition in which the robot armand the robot hand are coupled to each other, and TM an output signalfrom the timer circuit 121. The timer circuit 121 generates an outputsignal for a certain period of time T1 after the robot arm and the robothand are coupled to each other. During the period of time T1, thesignals LSl through LSn indicative of the operating conditions of theparts of the robot hand are ON and supplied via AND gates 122 in FIG. 9,after which the signals are converted to optical signals by thelight-emitting elements in the photoelectric transducer circuit 102.

With the present invention, as described above, the joint member on therobot body and the joint member on the robot arm are firmly joined toeach other by the engaging member which has the tapered surfaces fittedover one of the joint members. Therefore, a robot hand which isrelatively large and heavy can reliably be mounted on the robot body. Avariety of different robot hands can selectively be mounted easily onthe robot body to make the robot body highly versatile or usable invarious applications. Since the pipes for supplying the operatingmedium, the optical fibers, and the lead wires are not exposed, they areprotected from damage or breakage to allow robot hands to performdifferent operations effectively.

Plural pairs of optical signal transmitting means for transmittingcontrol signals across the mating surfaces of the robot hand and therobot arm are mounted in the first and second joint members on the robotarm and the robot hand such that the optical signal transmitting meansin each pair face each other out of contact, the robot arm and the robothand incorporating photoelectric transducer circuits, respectively.Accordingly, no mechanical contact is required when transmitting thecontrol signals, and the robot hand can easily be detached and attachedfor replacement. Even if the robot hand is replaced highly frequently,the optical signal transmitting means are not damaged, and hence theoptical signal transmission device is highly durable and reliable. Sinceonly the optical signal transmitting means are required to be disposedin place, the control signal transmitter may be smaller in size thanwould be if magnetic coupling were relied upon.

Moreover, one pair of optical fibers is employed at all times or for aprescribed period of time after the robot arm and the robot hand havebeen coupled to each other, and an optical signal is transmitted throughthe pair of optical fibers and detected at a predetermined light levelfor the detection of dirt on the mating surfaces. Such a dirt detectioncapability increases the reliability of robot operation.

As shown in FIG. 6, the set of optical fibers facing each other out ofcontact may be replaced with a pair of a light-emitting element such asan LED 200 and a light detector such as a phototransistor 300 which areembedded in the holder plates, and electric circuits may be incorporatedin the holder plates for performing the same functions as thosedescribed above.

Although certain preferred embodiments have been shown and described, itshould be understood that many changes and modifications may be madetherein without departing from the scope of the appended claims.

What is claimed is:
 1. A robot hand coupling assembly comprising:a firstjoint member mounted on a robot arm; a second joint member mounted on arobot hand; means for operatively connecting said first and second jointmembers, said means for operatively connecting comprising at least onemanifold, optical fiber members, electrical connector terminal andengaging means, having a plurality of radially extending teeth, saidteeth including slanted engaging surfaces mounted on each of said firstand second joint members and angularly movable relative thereto forpreventing a load exerted on said second joint member by the robot handfrom being locally imposed on said coupling assembly; actuator means forangularly moving said engaging means for detachably coupling said firstand second joint members, aid actuator means includes at least onecylinder including a rod connected to a rack mounted on said first jointmember, said engaging means includes a pinion meshing with said rackwhereby when said cylinder is operated to move said rod, said engagingmeans is angularly moved by said rack and said pinion for bringing saidfirst and second teeth into engagement with each other to couple saidfirst and second joint members; and fluid actuation means for enablingmovement of the robot hand upon connection of said coupling assembly. 2.A robot hand coupling assembly according to claim 1, wherein saidengaging means is fitted over said first joint member and has at leastone first tooth extending radially inwardly from an end of said engagingmeans which projects inwardly from said first joint member, said firsttooth having a first tapered surface, said second joint member having atleast one second tooth extending radially outwardly from an outerperipheral surface thereof at its one end, said second tooth beingengageable with said first tooth and having a second tapered surface,wherein when said one end of said second joint member including saidsecond tooth is inserted into said engaging means and said engagingmeans is angularly moved by said actuator means, said first and secondtapered surfaces are pressed against each other.
 3. A robot handcoupling assembly according to claim 1, wherein said first joint memberincludes at least one pin, and said second joint member includes a holein which said pin is fitted for positioning said first and second jointmembers with respect to each other.
 4. A robot hand coupling assemblyaccording to claim 1, wherein said means for operatively connectingcomprises first and second plates mounted respectively in said first andsecond joint members and holding said manifolds, optical fibers, andconnector terminals, the arrangement being such that when said first andsecond joint members are coupled to each other, said first and secondplates mate with each other to interconnect said manifolds, said opticalfibers, and said connector terminals for supplying the fluid actuationmeans to said robot hand.
 5. A robot hand coupling assembly comprising:afirst joint member adapted to be mounted on a robot arm; a second jointmember adapted to be mounted on a robot hand; means for supplying a handactuating medium through said first and second joint members to be robothand, said means for supplying including at least one manifold, opticalfiber and electrical connector terminals; engaging means having at leastone radially extending tooth, said engaging means being mounted on oneof said first and second joint members and angularly movable relativethereto; and actuator means for angularly moving said engaging means fordetachably coupling said first and second joint members, wherein saidactuator means includes at least one cylinder including a rod connectedto a rack mounted on said first joint member, said engaging meansincludes a pinion meshing with said rack, whereby said cylinder isoperated to move said rod, said engaging means is angularly moved bysaid rack and said pinion for bringing said first and second teeth intoengagement with each other to couple said first and second jointmembers.
 6. A robot hand coupling assembly according to claim 5, hereinsaid engaging mean sis fitted over said first joint member and has atleast one first tooth extending radially inwardly from an end of saidengaging means which projects inwardly from said first joint member,said first tooth having a first tapered surface, said second jointmember having at least one second tooth extending radially outwardlyform an outer peripheral surface thereof at its one end, said secondtooth being engageable with said first tooth and having a second taperedsurface, wherein said one end of said second joint member including saidsecond tooth is inserted into said engaging means and said engagingmeans is angularly moved by said actuator means, said first and secondtapered surfaces are pressed against each other.
 7. A robot handcoupling assembly according to claim 5, wherein said first joint memberincludes at least one pin, and said second joint member includes a holein which said pin is fitted for positioning said first and second jointmembers with respect to each other.
 8. A robot hand coupling assemblyaccording to claim 5, wherein said means for operatively connectingcomprises first and second plates mounted respectively in said first andsecond joint members and holding said manifolds, optical fibers, andconnector terminals, the arrangement being such that when said first andsecond joint members are coupled to each other, said first and secondplates mate with each other to interconnect said manifolds, said opticalfibers, and said connector terminals for supplying the fluid actuationmeans to said robot hand.